Touch screen panels are now ubiquitous and commonly used as the input and display interface, for example, in automatic teller machines, gambling machines in casinos, mobile communication devices, and navigation units. Touch screen panels generally comprise a transparent base substrate (for example, glass or polyethylene terephthalate (PET)) and a transparent conductive pattern (for example, indium tin oxide (ITO)) disposed on the base substrate. A conductive metal pattern (for example, copper or silver) is then formed on the edges of the transparent conductive pattern to provide a bus bar and to reduce the resistivity of the device.
A conductive metal pattern is typically adhered to a transparent conductive pattern by a conductive adhesive. In such a case, resistivity increases over a period of time as the conductive adhesive fails at high temperature and humidity. Other existing methods, such as silver frit, are costly and require special expensive indium solder to be used to attach wires thereto. Electro deposition of conductive metals is not feasible because of the poor current carrying capacity of the transparent conductive pattern material such as ITO. Similarly, electroless deposition of metals is challenging as the chemicals needed in the plating bath undergo undesirable side reactions with the transparent conductive pattern material such as ITO, which frequently lead to etching of the transparent conductive pattern material such as ITO during plating. Silver ink printing on the transparent conductive pattern material such as ITO is widely used to provide the bus bar. This method is very expensive and not suitable for fine pitch patterning.
Therefore, there remains a need to provide a patterning method that overcomes, or at least alleviates, the above problems.